Numerous manufacturing processes require the use of ultrapure liquids, such as acids, solvents, bases, photoresists, slurries, cleaning formulations, dopants, inorganic, organic, metalorganic and biological solutions, pharmaceuticals, and radioactive chemicals. Such applications require that the number and size of particles in the ultrapure liquids be minimized. In particular, because ultrapure liquids are used in many aspects of the microelectronic manufacturing process, semiconductor manufacturers have established strict particle concentration specifications for process chemicals and chemical-handling equipment. Such specifications are needed because, should the liquids used during the manufacturing process contain high levels of particles or bubbles, the particles or bubbles may be deposited on solid surfaces of the silicon. This can, in turn, lead to product failure and reduced quality and reliability.
Accordingly, storage, transportation, and dispensing of such ultrapure liquids require containers capable of providing adequate protection for the retained liquids. Two types of containers typically used in the industries are simple rigid-wall containers made of glass or plastic and collapsible liner-based containers. Rigid-wall containers are conventionally used because of their physical strengths, thick walls, inexpensive cost, and ease of manufacture. Such containers, however, can introduce air-liquid interfaces when pressure-dispensing the liquid. This increase in pressure can cause gas to dissolve into the retained liquid, such as photoresist, in the container and can lead to undesired particle and bubble generation in the liquids in the dispense train.
Alternatively, collapsible liner-based containers, such as the NOWPak® dispense system marketed by ATMI, Inc., are capable of reducing such air-liquid interfaces by pressurizing, with gas, onto the liner, as opposed to directly onto the liquid in the container, while dispensing. However, known liners may be unable to provide adequate protection against environmental conditions. For example, current liner-based containers may fail to protect the retained liquid against pinhole punctures and tears in the welds sometimes caused by elastic deformation from vibrations, such as those brought on by transportation of the container. The vibrations from transportation can elastically deform or flex a liner many times (e.g., thousands to millions of times) between the source and final destinations. The greater the vibration, the more probable that pinholes and weld tears will be produced. Other causes of pinholes and weld tears include shock effect, drops, or large amplitude movements of the container. Gas may be introduced through the pinholes or weld tears, thereby contaminating the retained liquids over time, as the gas will be permitted to go into the solution and come out onto the wafer as bubbles.
Additionally, collapsible liners are configured to be filled with a specified amount of liquid. However, the liners do not fit cleanly within their respective outer containers because folds are created in the liners as they are fit inside the containers. The folds may preclude liquid from filling the liners in the space taken up by the folds. Accordingly, when the container is filled with the specified amount of liquid, the liquid tends to overflow the container resulting in loss of liquid. As stated previously, such liquids are typically ultrapure liquids, such as acids, solvents, bases, photoresists, dopants, inorganic, organic, and biological solutions, pharmaceuticals, and radioactive chemicals, which can be very expensive, for example about $2,500/L or more. Thus, even a small amount of overflow is undesirable.
Thus, there exists a need in the art for better liner systems for ultrapure liquids that do not include the disadvantages presented by prior rigid-wall and collapsible liner-based containers. There is a need in the art for substantially rigid collapsible liners and flexible gusseted or non-gusseted liners. There is a need in the art for a liner-based storage and dispensing system that addresses the problems associated with pinholes, weld tears, gas pressure saturation, and overflow. There is a need in the art for liner-based storage and dispensing systems that addresses the problems associated with excess folds in the liner that can result in additional trapped gas within the liner. There is also a need in the art for liners that are comprised such that choke-off is limited or eliminated.